Superheater regulation



'pri 8 1924, 1,490,057

H. E. YARRow SUPERHEATER REGULATION Filed Apjril e, 1920 A4 sheets-sheet 2 April s 1924.

1,490,057 H. E. YARRQWL SAUPERHEATER REGULATION Filed April 6. 1920 y 4 Sheets-Sheet 3 l 1 l l April s 1924. 1,490,057

H. E. YARROW A SUPERHEATER REGULATION Filed April 6, 1920 4 Sheets-Sheet 4 wwf/Z Patented Apr. i924.

unirse ASTATES HAROLD E. YARROW, F GLASGOW, SCOILLAND.

SUPERHEATER REGULATION.

Application led April 6, 1920. Serial No. 371,746.

To aZZ whom t may concern.'

Be it known that I, HAROLD EDGAR YAR- Row, a subject of the King of Great Britain, residing in Glasgow, Scotland, have invented certain new and useful Improvements in or Relating to Superheater Regulation, of which the following is a specification.

The object of this invention is to provide means vwhereby the temperature to which the superheater of a steam generator is subjected is automatically controlled in accordance with the circulation of steam in the coils of the superheater, so that a high degree of superheat can be obtained for a full circulation of steam with safety to the superheater under all conditions.

According to the invention the temperature to which the coils of the superheater are subjected is made automatically dependent upon the diiierence of steam pressure between the inlet and outlet of the superheater by utilizing this difference of pressure to operate means for cutting olf or reducing the supply of combustible to the superheater burner or burners as the circulation of steam through the superheater diminishes. The invention will be hereinafter described more particularly with reference to a boiler of the Yarrow type in so which the superheater is provided with a local oil burner or burners of suiiicient capacity to produce the additional heat required for the desired degreek of superheat of the steam, but it must be understood that this particular embodiment of the invention is described purely by way of example.

In the accompanying drawings Fig. l is an end view, with certain parts shewn diagrammatically, of a Yarrow boiler provided with a superheater and-accessories embodying the invention, Fig. 2 isa vertical section shewing in detail one form of the automatic control device for the fuel supply; Fig. 3 is a similar view of another-form of control device; Fig. i is a sectional plan of another form of such device and Fig. 5 is a section of same taken on line 5-5 of Fig. 4: and Fig. 6 is a view partly diagrammatic embodying other modifications.

Referring first mainly to Fig. l A is the steam drum of a water tube boiler, B, B are the water drums thereof which are connected with the steam drum by banks of generating tubes.

drum communicates with one end of the superheater drum D which is provided with superheater tubes E through which the steam passes from the pipe C to the superheater outlet F, and thence to the engine or other consuming device which the boiler is designed to supply.

An oil burner G adapted to direct combustible into the interspace between the adjacent bank of steam generating tubes and the superheater tubes is supplied with oil through tube H from a supply tube I connected with a suitable source of oil fuel.

Between the tubes H and I there is interposed a valvular device consisting of a cylinder J and a piston K of such a character that, in one position of the piston, communication between the supply pipe I and the pipe H is cut ofi'. This position of the piston K is controlled by a mechanism comprising a cylinder L and a piston M, the upper end of the cylinder being connected by a pipeN with the outlet F of the superheater, and the lower end by a pipe O with the steam drum A or inlet end of the superheater. The rod M of the piston M may be rigidly connected with the rod K of the piston K as shown in Fig. 6 or, as shewn in Fig. l, they may be in alignment but not connected with each other. In either case the arrangement is such that when the difference in pressure between the inlet and outlet of the superheater is Zero (or falls to a predetermined value) the piston M assumes a position in the cylinder L, either under its own weight or assisted by a spring P, which causes the piston K to cut off communication between the pipes H and I and thus cuts olf the supply of liquid fuel to the burner or burners G. The piston yK is of such a character, e. g. by being-l made a leaky piston, that the oil pressure on both sides is the same. `When the cylinder .l is arranged vertically, as Ashown in Fig. 1, the piston K therein has a suiiiciently tight fit with said cylinder to sustain its own weight when raised to the position shown in Fig. l. Y

Such a piston is illustrated on an enlarged scale in Fig. 6, in Vwhich the piston K has a plurality of holes K3 connecting the spaces within the cylinder on the two sides of the piston so that both sides of the piston will be subjected to the same oil pressure.

So long as the ow of steam through the usi superheater is sufficient to cause such a transference of, heat as will prevent the superheater tubes from becoming overheated, the excess pressure on the under side of the piston M is suliicient to, prevent its descent to operate the piston It( so as to cut off the fuel supply to the burner G, but as soon as the-consumption of steam falls below this or ceases, the supply of oil fuel to the burner (l is automatically cut off as hereinbefore described. When the piston rods M", K are, as shewn in Fig. l, not rigidly connected, the restoration of the fuel supply to the burner G is effected manually when required.

It will be obvious that the valve arrangement controlling the supply of fuel to the burner Gr could be so arranged that instead of the piston K cutting oft the fuel supply absolutely when the conditions are such as might involve overheating of the superheater tubes, it may be arranged to cut off the supply only partially so as always to maintain a temperature sufficient to ignite the liquid or gaseous fuel used to heat the superheater tubes. `Such an arrangement might be desirable when the piston of the control cylinder L is rigidly connected with the piston of the valve cylinder J as shown .in Fig. G, and the valve is designed to control the supply of liquid or gaseous fuel to more ,than one local burner G, in Which case the valve might be arranged to cut off the supply of fuelabsolutely from the fuel supply pipes I-I leading to one or more of these burners and only partially or not at all from` the remainder thereof, so that upon the automatic establishment of the full supply to all the burners the local temperature would be suliicient to ignite the combustible issuing from the burners.

In the arrangement shown in Fig. 6 in which the piston rod M" of the motor cylinder L and the piston rod K of the valve cylinder J are rigidly connected, the doivnward movement of the piston K is arrested as by means of a collar K2 on the piston rod engaging a fixed stop L before the piston K cuts off communication between the lowest of the pipes ll and the oil supply pipe I.

In the modified arrangement of fuel con trol apparatus shewn in Fig. 2 the cont-rol cylinder L is, as before in communication on the under side of the piston M through pipe O with the steam space of the boiler, and on the upper side of the piston through pipe N with the outlet side of the superheater.

The piston rod M has at its free end a valve Q Which controls a port in the cylinder J in such manner that as long as the pressure in pipey O is greater than or sufliciently greater than the pressure in pipe N, this port Will be closed. Under such conditions the fuel supply to the burner or burners through inlet pipe I forces open the valve R Which is carried by the piston rod K of the leaky piston K, and passes through outlet H to the burner. If, however, the pressure difference on the two sides of piston M falls to Zero or some other predetermined value, the piston M drops and opens the valve Q, thereby relieving the pressure on the under side of the piston K through the port controlled by the valve Q and the relief pipe K0. Consequently the oil pressure on the upper side of the piston K operates this piston to close the valve R and so cut off the supply of fuel to the burner or burners.

In the alternative construction of controlling device illustrated in Fig. 3 the cylinder L is connected on one side of the piston M with the steam drum of the boiler through the pipe O, and on the other side of the piston M with the outlet of the superheater through the pipe N.

Under normal Working conditions the pressure of steam in pipe O is sufficient to maintain the piston M against the force of gravitation or that of a spring P, or both, in a position in which a valve Q carried by the piston closes a port S which would otherwise be in communication With the pipe N and which is connected by pipe S0 With a steam 95 cylinder U having a piston T rigidly or operatively connected with the piston rod K of the oil fuel piston valve K operating in the cylinder J and controlling the co-nnection between oil inlet I and outlet H lea-ding to the burner. Y

When the difference of pressure on the two sides of piston M is nil, or falls to a predetermined value, the valve Q is opened under the action of gravity or of the spring I, or 103 of both, and the pipe S0 is thus put in communication With the steam supply by connecton'With the pipe N. The steam pressure acting upon piston T operates the valve K to cut ofl" the supply of oil fuel from the burners. lVhen normal Working of the boiler is reestablished and the piston M closes the valve Q against the pressure of the spring P,'tlie pressure in the cylinder U above the piston T may be relieved by any suitable means, such as a cock, and the valve K maybe raised manually to the position shown in Fig. 3.

The controlling device illustrated in Figs. t and 5 is of a somewhat different character. In this apparatus a turbine or Pelton Wheel V, the inlet orifice IV of which is connected With the steam drinn or inlet side of the superheater and the exhaust IV with the outlet side of the superheater, is arranged to drive a gear pump X, X which delivers the oil admitted by the inlet pipe Io to the pump casing to the outlet H0 leading to the burner or burners. If there is no flou7 of steam through the superheater, or an insufficient flow to provide the requisite pressure dierence for driving the Pelton wheel, and the wheel stops, no oilcan iow through the gear pump X, X and consequently the oil supply to the burners is cut oli". It will be seen that this latter controlling device provides a convenient means for varying t-he deS livery of oil to the burners in accordance with the circulation of steam through the super-heater, that is to say in accordance with the consumption of steam by the engine or other consuming device supplied by the boiler.

Having thus described the nature of the said invention and the best means I know of carrying the same into practical effect, I claim l. In steam generators provided with superheaters means for automatically controlling the temperature to which the superheater is subjected, comprising a heating burner, a motor device actuated by the difference of steam pressure between the inlet and outlet of the superheater and a ,device controlling the supply of fuel to the heating burner and operated by the motor device, substantially as described.

2. In steam generators provided 'with superheaters, means for automatically controlling the temperature to which the superheater is subjected, comprising a heating burner, a valvular device controlling the supply of fuel to the burner and means for Y operating the valvular device actuated by the difference of steam pressure between the inlet and outlet of the superheater.

3. In steam generators provided with superheaters, means for automatically controlling the temperature to which the superheater is subjected, comprising a heating burner, a valvular device controlling the supply ofv fuel to said burner and a motor actuated by the difference of steam pressure between the inlet and outlet of the superheater and controlling the operation of the valvular device.

In testimony whereof I have signed my name to this specification.

HAROLD E. YARROW. 

